In the bowl of an electric mixer fitted with the dough hook attachment, add warm water, then yeast, melted butter, sugar, salt and 4 c. bread flour.
Turn on mixer, let mix until ingredients start to incorporate together and then add beaten eggs and 3 c. flour, one cup at a time, mixing in between. You may not need to add the full amount of flour, in fact I usually don’t. One of the keys to a good cinnamon roll is to not add too much flour. The dough will still be slightly tacky to the touch when it has enough flour. Knead on medium setting for 4 minutes. Cover bowl with a warm, damp towel or cling wrap and let rise for at least 30 minutes (or until doubled) in a warm place.
Roll out dough into a large rectangle on a lightly floured surface, about 1/4″ thick.
For the filling: spread softened butter over the dough and sprinkle with brown sugar and pat down. Sprinkle generously with cinnamon.
Roll dough up lengthwise and pinch the seams closed. You may need to get a little bit of water on your fingers and run it along the seam to get it to seal. Cut into about 2″ slices with dental floss or a serrated knife.
Place very close together on a greased or baking mat lined sheet or pan. Placing them close together will ensure that they will rise up nicely instead of out side to side, because tall cinnamon rolls are beautiful. It’ll also ensure that the sides stay nice and soft.
Let rise for at least 30 minutes, then bake in a 350 degree Fahrenheit oven for approximately 20-25 minutes. Let cool mostly before frosting or the frosting will melt.
For the buttercream frosting, cream the softened butter, powdered sugar and vanilla extract together in the bowl of an electric mixer. Add milk 1 Tbsp. at a time, mixing in between, until it’s nice and fluffy and creamy, but not runny (2-4 Tbsp. should do). Mix for at least 3 minutes for a really fluffy frosting!They’re the best when warm, and the first day, in my opinion!